US1177788A - Dynamo-electric machine. - Google Patents

Description

S. H. MARTIN.

` DYNAMO ELECTRIC MACHINE.

APPLICATION FILED IAN. 2. I9I5.

`Patented Apr. 4, 1916.

f .2. mi2@ i: figs SAMUEL H. MARTIN, OF CHICAGO, ILLINOIS.

DYNAMIC-ELECTRIC MACHINE.

Application led January 2, 1915. Serial No. 233.

To all ,1v/wm 'it may concern Be it known that I, SAMVEL H. MARTIN, a citizen ot' the'nited States 'of America, and a resident of Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Dynamo- Electric Machines` of which the following is a specification.

This invention relates to improvements in dynamo-electric machines, and more particularly to machines of this class adapted for motor service, and also-for the conversion of single or polyphase current into direct current and'vice versa.

The main objects ofthe invention are to provide an improved "construction and ar rangement of field members and electric circults for machlnes of the character dey scribed; to provide improved means for starting machines made in accordance with this invention A:to provide and arrange regulating' conductors both in the field and line circuits and also independently thereof for better control of speed; to provide an improved form of magnetic screen adapted to house and support the conductors of a squirrel cage and having electric circuits disposed thereon adapted to more effectually control the distribution and density of field flux nin starting and when operating under various conditions, and especially to suppress line surges and prevent hunting; to provide an improved form of squirrel cage structure adapted'toucact by repulsion upon the armature; to provide a machine adapted to start as a repulsion motor and to operate asa synchronous motor, and also having induction motor characteristics; to provide means for changing the motor circuit connections by a single switching operation from starting to running conditions, as for switching the motor current to the commutator 1n starting and to the collector rings for running; and to construct a machine of the character specified so as to permit of its being operated either as a motor or as a rotary converter. y

An illustrative embodiment of this invention is shown in the accompanying drawings, in whichp Figure 1 is a diagram showing circuit connections and a central cross section of a sinle phase alternating current machine, taken through the poles, in which view the col- Specication of Letters Patent.

rings upon the screen and thereby Patented Apr. 4, 1916.v

lector rings, commutator andarmature are shown by dotted lines. Fig. 2 is a frag;

rnentary view of the inner Side of the combined screen rlng and squirrel cage of'Fig.

l, developed in a planev for convenience in illustrating the relation of the various parts, the upper part of the View being in 'section along the line A-A of Fig. 1. Fig. 3 is a. fragmentary sectional view similar to a part of Fig. 1, but showing afmodified outside slotting of the screen member betweenthe poles.

In the construction shown in the drawings, the machine comprises a pair of relatively movable members, one of which is adapted and arranged to serve asi-a fieldmember 1 and the other as an armature 2. Said field member comprises an annular magnetic yoke 3 with projections or poles 4, and has thereon an annular member in the form of a being uniformly distributed and the teeth being perforated at 9. k

Squirrelcage members, referred to above,

are arranged concentrically in two substantially independent and dissimilar groups one of which comprises a continuous annulfr squirrel cage, and Athe 'other a segmental squirrel cage having its segments arrange( in series and preferablyjvith the ring see.- tors'at each end in the same plane respectively and spaced apart circumferentially.

The continuous squirrel cage comprises a pair of conductor rings or plates 12 disposed on oppositesides of the screen 5, and a seL ries of bars 13 and 14 disposed incertain of said slots 7 and in the perforations 9 respectively, said bars preferably bein adapted and arranged for clamping sai holding the squirrel cage and screen together inv a unitary and rigid manner. The bars 13 are preferably disposed in slots adjacent to the trailing edges of the poles 4 respectively.

Thesegmental o r multiple squirrel cage comprlses a pair of segmental rings or plates substantially like those of the continuous squirrel cage, except that each ring comprises a plurality of equal segments 17 insulated from one another and corresponding in number with the poles 4, said segments being insulated from one another at the points 17. The segments onone side of the screen are arranged each opposite a segment on the other side, and corresponding opposite segments are connected by .bars 18 adapted to clamp the segments in place and disposed incertain of the slots 7,

namely, those not occupied by the bars 13,

or the coils 20 and 21 hereinafter described midway between the poles 4. The segments of the vmultiple squirrel cage are all displaced angularly, somewhat, from registry with their respective poles, preferably about BSO/4P degrees in the direction of rotation, broaden the effective area of the poles. The bars 13 and 18 are preferably eXtra heavy as compared with the bars 14. Insulation rings or plates 23 separate the adjacent end rings, and insulation 24 surrounds the bars 13 and 18.

Each polar member or division of the segmental squirrel cage constitutes and serves as anv amortisseur grid, a squirrel cage and a repulsion member, and because of its angular displacement respecting the main poles 4 operates most eifectually as a motive member especially in starting. The continuous squirrel cage serves mainly as an induction secondary and as a damper or stabilizer.

In order to provide for controlling the field flux automatically the coils 20 and 21 are arranged preferably mid vay between the poles 4 on the ring 5 in the middle s lots 7. Said coils are ring wound and each pair may b e placed side by side in the same slot as shown, though this precise arrangement of coils respecting the slots is merely illustrative. The coils 20 are essentially shunt windings, as are the main field coils 25, and said coils 20 and 25 are preferably connected in series with one another across'the direct current brushes 26 on the commutator 27. Said coils `20 are connected to oppose magnetic leakage from the main polesthrough the screen. By this means the effect on the poles 4 of the continuous magnetic path of the induction motor stator is substantially neutralized and leakage prevented. The coils 21 are essentially series windings and are connected in series with the direct current line circuit, so as to further oppose magnetic*` leakage between the main poles. Moreover, the said coils 21 tend to strengthen the main poles and hold the neutral or commutation point at a fixed position. T hey also serve to magnetize the intermediate portions of the ring 5 adjacent to the edges of the poles v4 and thereby supplement and broaden the effective area of the poles. The direct current voltage lis thereby maintained nearly constant for all degrees of load. The coils 20 and 21 are formed of magnet wire, and are protected by insulation 28;

Motorv current of suitable phase, voltage and frequency is fed'to the machine through a double-throw switch 31 connected in a circuit leading to. a suitable v source 32. Said switch 31 is arranged to connect the motor current either to the brushes 26 and lcommutator 27, or to the brushes 34 and slip rings 35. Direct current may be supplied for any desired purpose as to lamps 37 on a clrcuit having a line switch 38.

j When a machine embodying the features of this invention is to be used as a converter to furnish direct current, it is necessary to provide means for controlling the polarity. In order to provide for such control, a switch 40 is preferably connected in the shunt eld circuit. If, upon starting` the machine, the voltage across the brushes 26 is not in the right direction, said switch 40 may be opened and closed, which operation may be repeated until the desired polarity is produced. The same result may be accomplished by opening the motor switch 31 but with4 less efficiency and convenience. When the machine is to be used for motor service only the switch 40 may be omitted as the matter of field polarity is material only when direct current is to be taken from the machine.

Slots 42 are preferably provided in vthe magnetic ring 5 in the side oppositeY from the slot 7 and adjacent to the edges of the poles 4. The said slots 42 serve to restrict or choke the leakage path of the field flux and thereby assist in controlling the field. lith the slots 42 arranged as stated. they serve especially when the machine is lightly loaded, to concentrate the field strength iinmediately under the poles 4 and thereby help to hold the neutral or commutation point in a. fixed or nearly fixed position, which is important when the machine is to be -used as a converter. Vhcn the direct current line is loaded the series coils 21 energize. the ring 5 between the adjacent slots 42 respectively so as virtually to strengthen the field. 'hen the machine is to be used solely as a motor the coils 21 are omitted. and a single slot 43 shown on Fig. 3, may be provided midway between each pair of poles 4 in place of the slots 42. ln this instance the slots 43 restrict the magnetic leakage and the coils 20 neutralize land oppose leakage.

Said slots 42 and 43 serve the same'or likel purpose in polyphase machines.

The operation-of' the machine is as follows: ln starting, the motor switch 31 is thrown to the left. whereby alternating current is fed to the armature through the com mutator. The machine starts mainly as an inverted repulsion motor, induction motor 4'features assisting. When the machine has 'come up to synchronous speed, the said -sjwitch isl thrown over to its running position., whereby the motor current is `fed vthrough the slip rings. The machine runs normally .as a synchronous converter or inotor, -ant in case of overload is assisted by the, induction motor members. The supply .of direct current from the machine is controlled by the switch 38.

This invention is an improvement over the devices of my copending applications, Serial No. 716,407 filed August 22, 1912,' and- Serial No. 771,172 filed June 2, 1913, and distinguishes therefrom mainly in the multiple and segmental character of the inductionsecondary or squirrel cage, and in the angular displacement thereof, or of certain 4of its parts, with respect to the physical poles of the machine, and in the provision of reluctance apertures or slots disposed transversely in the outer side of the screen to diminish leakage of flux through said screen between the polar projections 4.

Although but one specific embodiment of this invent-ion has been herein shown and described, it will be understood that numerous details of the construction shown may be altered or omitted without departing from the spirit of this invention as defined by the following claims.

1. In a dynamo-electric machine, a pair of relatively movable members, one of which comprises a plurality of annular squirrel cage members concentrically disposed, one of said squirrel cage members being segmental in form.

2^. A dynamo-electric machine, compris- Ving a field member having polar projections thereon, a magnetic i'ing embraced by saidpolar projections, a relatively movable inember coaxially disposed with respect to said.

field member, said magnetic ring having an annular squirrel cage structure disposed adjacent to said movable member, and also a segmental squirrel cage structure insulated from and independent of the first mentioned squirrel cage structure, and also disposed adjacent to said movable member. t

3. A dynamo-electric machine, comprising a field member having polar projections thereon, avmagnetic ring'embraced by said polar projections, a relatively movable niember coaxially disposed with respect to said field member, said magnetic ring having an annular squirrel cage structure disposed adjacent to said movable member, .and also a segmental squirrel cage structure insulated from and independent of the first mentioned ments of said segmental structure being' structure comprising ka magnetic ring, a pair of conductor rings disposed on opposite sides of said magnetic ring, conductor bars spaced apart around said magnetic ring and connecting said conductor rings, a pair of segmental conductor rings also disposed on opposite sides of said magnetic ring, the sectors whereof are each insulated, and the sectors on 011e side of said magnetic ring being disposed to register with corresponding sectors on the opposite side, and another series of conductor bars spaced apart around said magnetic ring and connecting cori'esponding segments on opposite sides of said magnetic ring, there being a plurality of the last mentioned bars for-each pair of said sectors.

y5. A dynamo-electric machine comprising a field member having polar projections thereon, a relativelyv movable member c0- axially disposed with respect to said field member, said polar projections being disposed to face toward said movable member, a magnetic ring adapted to serve as a screen disposed between said polar projections and movable member and carried rigidly by said polar projectimis. said magnetic ring having an annular squirrel cage structure carried thereby andv disposed adjacent to said movable member, and a series of independent closed circuit members corresponding in relative position to said polar projections respectively.

6. In a dynamo-electric machine, a field ring having polar projections thereon in combinationwith a structure comprisingl a `magnetic ring carried rigidly by said polar projections, a pair of conductor rings disposed on opposite sides of said magnetic ring, coiiductoi ba rs spaced apart around said ma gnetic ring and connecting said` conductor rings, and a series of close-d circuit conductor members disposed upon and carried by said magnetic ring adjacent to the said polar projections respectively, and displaced angularly therefrom in the same direction around said magnetic ring.

7; In a dynamo-electric-'niachine, a yoke member having inwardly facing polar projections with shunt field windings thereon, an armature arranged to rotate within the said polar projections, a. continuous inagnetic ring disposed between said polar projections and said armature and embraced rigidly by said polar projections, an annular squirrel cage carried by said magnetic ring,

tively, and ring wound series windings disposed on said magnetic 'ring between said polar projections.

8. In a dynamo-electric machine, a yoke member `having inwardly' facing polar projections with shunt field windings thereon, an armature arranged to rotate within the said polar projections, a continuous magnetic ring disposed between said polar projections and said armature and embraced rigidly by said polar projections, an annular squirrel cage carried by said magnetic ring, said armature having a commutator and slip rings, brushes for said commutator and slip rings respectively, and both shunt and series ring wound coils disposed on said magnetic ring betweensaid polar projections.

9.' A dynamo-electric machine comprising a field yoke having polar projections thereon, a relatively movable member coaxially disposed with respect to said field yoke, said polar projections being disposed to face toward said movable member, a magnetic ring disposed between said polar projections and movablei member and carried rigidly b v said polar projections, a continuous annular squirrel cage carried by said ring adjacent to said movable member, said squirrel cage having a series of relatively small conductor bars distributed around said squirrel cage and relatively large bars disposed adjacent to the trailing edges of said polar projections respectively.

10. A dynamo-electric machine comprising a iield member having polar projections thereon, a relatively.movable member coaXially disposed with respect to said iield member, said polar projections being arranged to face toward said movable member. and a magnetic ring disposed between said polar projections and movable member and carried rigidly by said polar projections. said magnetic ring .being separated from said mo vable. memberby a suitable air gap. and also being fornied and arranged on the side facing said movable member to carry conducfr." and the opposite side to face toward said movable member, a mag' netic ringr disposed between said polar pron jections and movable member and carried rigidly by said polar projections, and a ring-wound coil on said magnetic ringfbetween each pair of adjacent polar projections, said ring being slotted transversely adjacent to the edges ot' said polar projec- --l tions to concentrate the flux from said polar projections and restrict magnetic leakage, and said coil' Vbeing series connected and arranged to strengthen and broaden the effective pole area when a direct current load is thrown upon the machine.

12. A dynamo-electricconverter comprising a stationary voke having polar projections thereon, a rojtary armature disposed coaxially with respect to said yoke, said polar projections being disposed to face toward said armature, a magnetic ring disposed between said polar projections and armature and carried rigidly by said polar projections. said ring having squirrel cage members disposed about its inner surface adjacent to said armature and having transverse slots disposed adjacent to the edges of said polar projections adapted to limit spreading of the magnetic flux from said polar projections. and ring wound coils dis posed on said ring between said polar projections. said coils being connected in series to the direct current side -of thefarmature and arranged to supplement andmbroaden the effective area of the poles.

Signed at Chicago this 31st day of Dec.,-

SAMUEL H. MARTIN. lVitnesses:

FRED M. Davis, lY-iLLIAM E. HAXN.

onnection in Leners Ptem No. 1,177,788

l vIt. is hereby certified that in Letters Patent No. 1,177,788, gred April 4, 1916, upon the application of Samuel H, Martin, of Chicago, Illinois, for an improve ment in Dynumo-Eleetrie Machines, an error appears the printed lspecific'at'iorn requiring correction as follows: lage 2,

letter P .fjepresenting'the numbef of poles;

` ord of the case iii the Patoiit Office.A

Signed andsealed this 2d. dey of May, A." D., 1916'. l

[SEAL] R; F. WHITEHEAD,

\ Act'in Oommiaamf of Patents. C1. 1'71-123.

strike out line 22 and insert the words and l The; andtlat the .said'Letters Patent,

should beread with this correction therein that the sal-ne `'may4 conform to the rec- It is hereby certied that in Letters Patent No. 1,177,788, grantedv April 4, 1916,

upon the application of Samuel H, Martin, of Chicago, Illinois, for an improvement in Dynamo-Electric Machines," an error appears the printed specification requiring correction as follows: Page 2, strike out line 22 and insert the words and n letter Prepresenttng'the number of poles.' The; and that the -sad'Letters PatentA should be read with this correction therein that the saine 'may conform to the record of the case in the Patent Oilice.' l

Signed and -sealed this 2d. day of May, A.v D., 1916-.

{SEAL} n; WHITEHEAD,

' my ammissione ofPatmzs.

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